R.C.C.STRUCTURE
UNIT I
1. State the drawbacks and limitations of working stress method.
2. What do you understand by balanced, under reinforced and over reinforced
section? Explain with the help of stress diagram.
3. Determine moment of resistance of a singly reinforced beam 160 mm wide and
300 mm deep to the centre of reinforcement, if the stresses in steel and concrete
are not to exceed 140 Mpa and 5 Mpa. Total area of steel provided is 8.04 cm 2
.If the beam is used over an effective span of 5 m find the maximum load the
beam can carry, inclusive of self weight. Take m=18. Use working stress
method.
4. A reinforced concrete beam of rectangular section 300 mm wide by 650 mm
deep is reinforced with 4 bars of 32 mm diameter at an effective depth of 600
mm using M20 grade concrete and Fe 415 HYSD bars, estimate the moment of
resistance of the section.
5. Explain various systems for prestressing and enlist the losses in prestressing.
6. A prestressed concrete beam 300 mm wide and 450 mm deep is prestessesed
with steel wire of cross sectional area 250 mm2 located at constant eccentricity
of 50 mm carrying an initial stress of 1100 N/ mm2 The span of the beam is
12m. calculate the percentage loss of stress in wire if the beam is pretensioned
and the beam is post tensioned using following data:- Es=200 KN/mm2, Ec = 40
KN/ mm2 Relaxation of steel stresses = 5 % of initial stress, shrinkage of
concrete = 300 x 10 -6 units for post tensioning. Creep coefficient = 1.5, slip at
anchorage = 1.5 mm, friction coefficient for wave effect= 0.0010 per m.
7. A prestressed concrete composite beam centr to centr spacing of beams is 2
metres. Young’s Modulus of concrete for prestressed concrete is 0.3x105 N/
mm2 and the modular ratio of Young’s modulus of concrete for the cast in situ
concrete and prestressed concrete is 0.8. The shrinkage is 1.5 x 105-4 mm/mm.
Determine the shrinkage stresses at the top and bottom of slab and at top and
bottom of I- beam.
8. Explain with the help of neat sketches following prestressing systems:
i)
Freyssinet system
ii)
Magnel-Blaton system
iii)
Gifford Udall system
UNIT II
9. Define characteristic load & partial safety factors.
10. State the modes of failure of a R.C. member in flexure.
11. Formulate from fundamental the expression for depth for critical neutral
axis(nd).Lever arm(jd) and moment of resistance (Q) for balanced rectangular
singly reinforced section.
12. A reinforced concrete rectangular beam of overall dimensions 250 mm x
600mm is reinforced with 4x20 mm Ф bars in tension at an effective cover of
40 mm. The beam supports a brick wall 250 mm which and H high over a
simply supported span of 4.5 m. Calculate the height H of wall the beam can
support. Assume density of brick masonry as 20 KN/m3. Use M20 concrete and
Fe415 steel.
13. A reinforced concrete beam is to be designed over an effective span of 5m to
support a design service load of 8 KN/m. Adopt M-20 grade concrete and Fe415
HYSD bars and design the beam to satisfy the collapse and serviceability limit
states.
14. Determine the area of reinforcement required for a singly reinforced concrete
section having a breadth of 300 mm and an effective depth of 600 mm to resist a
factored moment of 200 KNm. Adopt fck = 20 N/ mm2 and fy = 415 N/ mm2 .
15. Determine the minimum effective depth required and te corresponding area of
tension reinforcement for a rectangular beam having a width of 200 mm to resist
an ultimate moment of 200 KNm. Using fck = 20 N/ mm2 and fy = 415 N/
mm2 .
16. Explain the limit state of collapse.
UNIT III
17. Calculate moment of resistance of T section shown in fig. Grade of concrete =
M20,Grade of steel = Fe415.Width of flange = 1500 mm, Depth of flange =
100mmDepth of beam = 600 mm, Width of rib = 300 mm, Area of tension
reinforcement is 3473 mm2. Take effective cover = 65 mm
18. Calculate the moment of resistance of an isolated T beam of following
properties; i)width of flange= 2500 mm ii)simply supported span= 6M iii)
thickness of flange = 150 mm iv) depth of rib = 350 mm v) width of rib = 230
mm vi) Area of tension steel = 4 NOs. of 16 mm dia. Fe415 vii) effective
cover= 50 mm viii) use M20 grade of concrete. Calculate area of steel for
balanced section.
19. A tee beam has an effective flange width of 2500 mm and depth of flange is 150
mm, width pf rib is 300 mm, effective depth is 800 mm. Using M20 grade
concrete and Fe 415 HYSD bars, estimate the area of tension reinforcement
required if te section has to resist a design ultimate moment of 1200 KNm.
20. Design axially loaded circular column with M20 grade and Fe415. Design the
helical rings. Axial load on column = 1000KN. Assume diameter of column=
350 mm.
21. A R.C.C. square column of 3.5 m effective length is required to resist an axial
load of 1750 KN. Design column using M20 grade of concrete and Fe415 grade
of steel. Assume that unsupported length and effective length are equal.
22. Design the reinforcement in a spirally tied column of 400 mm diameter,
supporting an axial factored load of 1500 KN. The column has an unsupported
length of 3.4 m and is braced against side sway. Adopt M25 and Fe 415.
23. Design the reinforcement in a short column 400 mm by 600 mm subjected to an
ultimate axial load of 1600 KN together with an ultimate moments of 120 KNm
and 90 KNm about the major and minor axis resp. Adopt M25 and Fe 415.
UNIT IV
24. Design shear reinforcement for a beam with b=350 mm, d= 550 mm. Ultimate
shear force = 125 KN. Percentage of steel is 1.67 percent. Use M25 mix concrete
and Fe415 steel.
25. Explain limit state of serviceability.
26. Explain development length.
27. Write notes on deflection control of beam and one way slab.
28. A reinforced concrete beam has a support section with a width of 250 mm and
effective depth of 500 mm. The support section is reinforced with 3 bars of 20
mm diameter on the tension side 8 mm diameter 2 legged stirrups are provided
at a spacing of 200 mm centers. Using M20 grade concrete and Fe 415 HYSD.
Calculate the shear strength of the support section.
29. Design the development length for steel in above section.
30. Explain cracking in structural member.
31. Explain short term deflection and long term deflaction.
UNIT V
32. A rectangular R.C.C. tank is required to store 10,000 liters of water. Depth of
water in the tank= 3m. Free board = 0.2 m. Adopt M20 concrete and Fe415
HYSD bars. Tensile stresses in steel limited to 100 N/ mm2 at water face and
125 N/ mm2 away from water face. Sketch the details of reinforcement in the
walls of the tank.Use Approximate method for calculation of wall thickness.
33. Design a circular water tank resting on firm ground. The capacity of tank is 300
m3 The depth of water is 2.5 m. Take free board of 0.5 m. Design 1) The wall of
tank 2) Top dome 3) Top ring beam at the junction of wall and dome. Use M20
concrete and Fe 415 steel. Show reinforcement details.
34. A rectangular R.C.C. tank is required to store 12,000 liters of water. Depth of
water in the tank= 3m. Free board = 0.2 m. Adopt M20 concrete and Fe415
HYSD bars. Tensile stresses in steel limited to 100 N/ mm2 at water face and
125 N/ mm2 away from water face. Sketch the details of reinforcement in the
walls of the tank.Use IS code method for calculation of wall thickness.
35. A pretensioned beam of rectangular section 80 mm wide and 120 mm deep I to
be designed to support concentrated loads of 4 KN each at one third span points
over an effective span of 3m. The permissible stresses in concrete are limited to
zero and 1.4 N/ mm2 tension at transfer and working load resp. If 3 mm
diameter wires initially stressed to 1400 N/ mm2 are used find the number of
wires required and the eccentricity of the prestressing force assuming 20 % loss
in prestress. Take weight of concrete= 24 KN/m3
36. A presstressed concrete rectangular beam 30 mm x 600mm is presstressed with
a force 1565 KN applied at 180 mm from the bottom the force finally reducing
to 1361 KN. The span of beam is 12.2 m and carries two equal live loads 45 KN
each at a distance of 4.6 m from each support. Find the extreme fiber stresses at
the mid- span under i) initial prestress and no live load and final conditions.
Assume specific weight of concrete = 24 KN/m3
37. A prestressed concrete T beam is to be designed to support an imposed load of 4
KN/m over an effective span of 5 m. The flange is 400 mm wide and 40 mm
thick, rib is 100 mm wide and 200 mm deep. Yhe stress in concrete must not
exceed 15 N/ mm2 in compression and zero in tension at any stage. Check for
the adequacy of the section provided and calculate the minimum prestressing
force necessary and corresponding eccentricity.
UNIT VI
38. Design a R.C. square pad footing for a column of section 400 mm x 400 mm
subjected to a load of 1200 KN at service state. Take safe bearing capacity of
soil = 150 KN/ m2 ,Wt of soil = 20 KN/m3 . Take depth of footing below ground
level = 2m. Use M20 grade concrete and Fe415 grade steel. Draw reinforcement
details.
39. A hall of effective dimensions 8mx15m is provided with beams at 3 m c/c
forming five slab panels each of 3mx8m(effective). Design the slab panels as
continuous slab using limit state method for following data:- 1) Live load 4
KN/m2 2) Finishing load 1 KN/m2 3) M20 concrete and Fe415 steel. Provide all
checks and sketch the reinforcement details.
40. Design a rectangular pad footing for a column of section 300 mm x 450 mm
subjected to an axial load of 1000 KN at working conditions. Assume the SBC
of soil as 200 KN/ m2. Use M20 concrete and Fe415 steel. Draw neat sketch of
reinforcement details.
41. Design a one way slab with a clear span of 3.5 m, simply supported on 200 mm
thick concrete masonry walls to support a live load of 4 KN/ m2 . Adopt M20
grade and Fe415 HYSD bars.
42. Design a cantilever chajja slab projecting 1m from the support using M20 grade
concrete and Fe415 HYSD bars. Adopt a live load of 3 KN/ m2
43. Design a dog legged stair case (waist slab type) for an office building assuming
floor to floor height of 3m. Width of flight = 1.2 m, landing width = 1.2 m.
Adopt a tread of 300 mm and rise of 150mm. Use M20 grade concrete and
Fe415 HYSD bars. Live load 5KN/ m2 . Assume the landing to be supported
only on two edges perpendicular to the risers.
44. Design open well type stair case for a multi storey office complex using the
following data. Length of each flight = 1.5 m (5 tread in each flight), Length of
landings= 1m, Tread = 300 mm and riser = 150 mm, The landings are supported
all round on 300 mm masonry walls. Live load = 5 KN/ m2. fck= 20 N/mm2 ,
fy=415 N/mm2
45. Design a singly reinforced concrete beam to suit the following data.
Clear span = 4m
Width of supports = 300 mm
Service load = 5 KN/m
Use M20 & Fe415